Gas delivery apparatus for atomic layer deposition

ABSTRACT

An apparatus and method for performing a cyclical layer deposition process, such as atomic layer deposition is provided. In one aspect, the apparatus includes a substrate support having a substrate receiving surface, and a chamber lid comprising a tapered passageway extending from a central portion of the chamber lid and a bottom surface extending from the passageway to a peripheral portion of the chamber lid, the bottom surface shaped and sized to substantially cover the substrate receiving surface. The apparatus also includes one or more valves coupled to the gradually expanding channel, and one or more gas sources coupled to each valve.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims benefit of U.S. Provisional Patent ApplicationSer. No. 60/397,230, filed on Jul. 19, 2002, and entitled “ImprovedDeposition Apparatus”, which is incorporated by reference herein. Thisapplication also claims benefit of U.S. Provisional Patent ApplicationSer. No. 60/346,086, filed on Oct. 26, 2001, and entitled “Method andApparatus for ALD Deposition”, which is incorporated by referenceherein. This application is also a continuation-in-part of U.S. patentapplication Ser. No. 10/032,284, filed on Dec. 21, 2001, and entitled“Gas Delivery Apparatus And Method For Atomic Layer Deposition”, whichis incorporated by reference herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

Embodiments of the present invention generally relate to an apparatusand method for atomic layer deposition. More particularly, embodimentsof the present invention relate to an improved gas delivery apparatusand method for atomic layer deposition.

2. Description of the Related Art

Reliably producing sub-micron and smaller features is one of the keytechnologies for the next generation of very large scale integration(VLSI) and ultra large scale integration (ULSI) of semiconductordevices. However, as the fringes of circuit technology are pressed, theshrinking dimensions of interconnects in VLSI and ULSI technology haveplaced additional demands on the processing capabilities. The multilevelinterconnects that lie at the heart of this technology require preciseprocessing of high aspect ratio features, such as vias and otherinterconnects. Reliable formation of these interconnects is veryimportant to VLSI and ULSI success and to the continued effort toincrease circuit density and quality of individual substrates.

As circuit densities increase, the widths of vias, contacts, and otherfeatures, as well as the dielectric materials between them, decrease tosub-micron dimensions (e.g., less than 0.20 micrometers or less),whereas the thickness of the dielectric layers remains substantiallyconstant, with the result that the aspect ratios for the features, i.e.,their height divided by width, increase. Many traditional depositionprocesses have difficulty filling sub-micron structures where the aspectratio exceeds 4:1, and particularly where the aspect ratio exceeds 10:1.Therefore, there is a great amount of ongoing effort being directed atthe formation of substantially void-free and seam-free sub-micronfeatures having high aspect ratios.

Atomic layer deposition is one deposition technique being explored forthe deposition of material layers over features having high aspectratios. One example of atomic layer deposition comprises the sequentialintroduction of pulses of gases. For instance, one cycle for thesequential introduction of pulses of gases may comprise a pulse of afirst reactant gas, followed by a pulse of a purge gas and/or a pumpevacuation, followed by a pulse of a second reactant gas, and followedby a pulse of a purge gas and/or a pump evacuation. The term “gas” asused herein is defined to include a single gas or a plurality gases.Sequential introduction of separate pulses of the first reactant and thesecond reactant may result in the alternating self-limiting adsorptionof monolayers of the reactants on the surface of the substrate and,thus, forms a monolayer of material for each cycle. The cycle may berepeated to a desired thickness of the deposited material. A pulse of apurge gas and/or a pump evacuation between the pulses of the firstreactant gas and the pulses of the second reactant gas serves to reducethe likelihood of gas phase reactions of the reactants due to excessamounts of the reactants remaining in the chamber.

However, there is a need for a new apparatus to perform gas delivery andto perform deposition of films by atomic layer deposition.

SUMMARY OF THE INVENTION

An apparatus and method for performing a cyclical layer depositionprocess, such as atomic layer deposition is provided. In one aspect, theapparatus includes a substrate support having a substrate receivingsurface, and a chamber lid comprising a tapered passageway extendingfrom a central portion of the chamber lid and a bottom surface extendingfrom the passageway to a peripheral portion of the chamber lid, thebottom surface shaped and sized to substantially cover the substratereceiving surface. The apparatus also includes one or more valvescoupled to the gradually expanding channel, and one or more gas sourcescoupled to each valve.

In another aspect, the apparatus includes a substrate support having asubstrate receiving surface, a chamber lid comprising an expandingchannel extending downwardly to a central portion of the chamber lid andcomprising a conical bottom surface of the lid extending from theexpanding channel to a peripheral portion of the chamber lid, and one ormore gas conduits disposed around an upper portion of the expandingchannel, wherein the one or more gas conduits are disposed at an anglefrom a center of the expanding channel. The apparatus also includes oneor more valves coupled to the gradually expanding channel, and a chokedisposed on the chamber lid adjacent a perimeter of the conical bottomsurface.

In one aspect, the method comprises: providing one or more gases intothe substrate processing chamber in an initial circular direction over acentral portion of the substrate; reducing the velocity of the gasesthrough non-adiabatic expansion; providing the gases to a centralportion of the substrate; and directing the gases radially across thesubstrate from the central portion of the substrate to a peripheralportion of the substrate at a substantially uniform velocity.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features of the presentinvention are attained and can be understood in detail, a moreparticular description of the invention, briefly summarized above, maybe had by reference to the embodiments thereof which are illustrated inthe appended drawings.

It is to be noted, however, that the appended drawings illustrate onlytypical embodiments of this invention and are therefore not to beconsidered limiting of its scope, for the invention may admit to otherequally effective embodiments.

FIG. 1 is a schematic cross-sectional view of one embodiment of achamber including a gas delivery apparatus adapted for atomic layerdeposition.

FIG. 2A is a schematic cross-sectional view of one embodiment of a chokedisposed on a lower surface of a chamber lid.

FIG. 2B is a cross-sectional view of an alternative embodiment of achoke disposed on a lower surface of a chamber lid.

FIG. 3 is a schematic cross-sectional view of an alternative embodimentof a chamber including a gas delivery apparatus adapted for atomic layerdeposition.

FIG. 4 is a schematic, cross-sectional view of a valve showing the valveinlets and outlets.

FIG. 5 is a schematic plan view of an exemplary valve shown in FIG. 4.

FIG. 6 is a schematic cross-sectional view of one embodiment of a valveillustrating the internal components and mechanisms of the valve.

FIG. 7 is a graph of a diaphragm moved between an open position and aopen position.

FIG. 8 is a horizontal sectional view of one embodiment of an expandingchannel formed within the gas delivery apparatus of the presentinvention.

FIG. 9 is a horizontal sectional view of one embodiment of the expandingchannel adapted to receive a single gas flow.

FIG. 10 is a horizontal sectional view of one embodiment of theexpanding channel adapted to receive three gas flows.

FIG. 11 is a cross-sectional view of the expanding channel formed withinthe gas delivery apparatus of the present invention.

FIG. 12 is a schematic cross-sectional view illustrating the flow of agas at two different positions between the surface of a substrate andthe bottom surface of the chamber lid 1.

FIG. 13 is a schematic cross-sectional view of another embodiment of achamber including a gas delivery apparatus adapted for atomic layerdeposition.

FIG. 14 shows another embodiment of a chamber including a gas deliveryapparatus adapted for atomic layer deposition.

FIG. 15 is a schematic view of a gas box useful with the gas deliveryapparatus of the present invention.

FIG. 16 is a schematic cross-sectional view of one embodiment of acanister for generating a gas via sublimation within the gas box of FIG.15.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 1 is a schematic partial, cross-sectional view of an exemplaryprocessing system 200 capable of performing cyclical layer deposition,atomic layer deposition, digital chemical vapor deposition, and rapidchemical vapor deposition techniques. The terms “cyclical layerdeposition”, “atomic layer deposition”, “digital chemical vapordeposition”, and “rapid chemical vapor deposition” are usedinterchangeably herein and refer to gas phase deposition techniqueswhereby two or more compounds are sequentially introduced into areaction zone of a processing chamber to deposit a thin layer ofmaterial on a substrate surface.

The chamber 200 includes a chamber body 202, a gas delivery system 230,a vacuum system 278, and a control unit 280. The chamber body 202 hassidewalls 204, a bottom 206, and a liner 299. A slit valve 208 is formedin a sidewall 204 of the chamber body 202 to provide access for a robot(not shown) to deliver and retrieve a substrate 210, such as a 200 mm or300 mm semiconductor wafer or a glass substrate, from the chamber 200.

A substrate support 212 is disposed within the chamber body 202 tosupport a substrate 210 on a substrate receiving surface 211 thereon. Alift motor 214 raises and lowers the substrate support 212. A lift plate216 connected to a lift motor 218 is mounted in the chamber 200 andraises and lowers pins 220 movably disposed through the substratesupport 212. The pins 220 raise and lower the substrate 210 over thereceiving surface 211 of the substrate support 212. The substratesupport 212 may include a vacuum chuck, an electrostatic chuck, or aclamp ring for securing the substrate 212 to the substrate support 212during processing. The substrate support 212 may also be heated to heata substrate 210 disposed thereon. For example, the substrate support 212may be heated using an embedded heating element, such as a resistiveheater, or may be heated using radiant heat, such as heating lampsdisposed above the substrate support 212.

The chamber body 202 also includes a purge ring 222 disposed on thesubstrate support 212 to define a purge channel 224. A purge gas flowsthrough the purge channel 224 to a peripheral portion of the substrate210 to prevent deposition thereon.

The vacuum system 278 is in communication with a pumping channel 279formed within the sidewall 204 of the chamber body 202. The vacuumsystem 278 evacuates gases from the chamber body 202 and maintains adesired pressure or a desired pressure range inside a pumping zone 266of the chamber 202. The pumping zone 266 is formed within the chamberbody 202, surrounding the substrate support 212.

The gas delivery system 230 and the chamber body 202 define a reactionzone 264 within the chamber body 202. The reaction zone 264 is in fluidcommunication with the substrate support 212. More particularly, thereaction zone 264 includes any volume within the chamber 200 that isbetween a gas source and the substrate surface. A reactant gas or purgegas can adequately fill the reaction zone 264 and ensure sufficientexposure of the substrate 210 to the reactant gas or purge gas. Inconventional chemical vapor deposition, prior art chambers are requiredto provide a combined flow of reactants simultaneously and uniformly tothe entire surface of the substrate in order to ensure that theco-reaction of the reactants occur uniformly across the surface of thesubstrate. In atomic layer deposition, the chamber 200 sequentiallyintroduces reactants to the substrate surface to provide adsorption ofalternating thin layers of the reactants onto the surface of thesubstrate. As a consequence, atomic layer deposition does not require aflow of reactants which reach the surface of the substratesimultaneously. Instead, a flow of each reactant needs to be provided inan amount which is sufficient for a thin layer of the reactant to beadsorbed on the surface of the substrate.

Since the reaction zone 264 contains a smaller volume compared to aninner volume of a conventional CVD chamber, a smaller amount of gas isneeded to fill the reaction zone 264 for a particular process. Forexample, in one embodiment, the volume of the reaction zone 264 is about1000 cm³ or less, preferably 500 cm³ or less, and more preferably 200cm³ or less for a chamber adapted to process 200 mm diameter substrates.In one embodiment, the volume of the reaction zone 264 is about 3,000cm³ or less, preferably 1,500 cm³ or less, and more preferably 600 cm³or less for a chamber adapted to process 300 mm diameter substrates. Inone embodiment, the substrate support 212 may be raised or lowered toadjust the volume of the reaction zone 264 for deposition. Because ofthe smaller volume of the reaction zone 264, less gas, whether adeposition gas or a purge gas, is necessary to be flowed into thechamber 200. Therefore, the throughput of the chamber 200 is greater andwaste may be minimized due to the smaller amount of gas used, reducingthe cost of operation.

In the embodiment of FIG. 1, the gas delivery system 230 is disposed atan upper portion of the chamber body 202 to provide a gas, such as aprocess gas and/or a purge gas, to the chamber body 202. The gasdelivery system 230 includes a chamber lid 232 and an expanding channel234 formed therethrough. The chamber lid 232 includes a bottom surface260 that is sized and shaped to substantially cover the substrate 210disposed within the chamber body 202.

At least a portion of the bottom surface 260 of the chamber lid 232 maybe tapered from the expanding channel 234 to a peripheral portion of thechamber lid 232 to provide an improved gas velocity profile across thesurface of the substrate 210 (i.e., from the center of the substrate tothe edge of the substrate). The bottom surface 260 may include one ormore tapered surfaces, such as a straight surface, a concave surface, aconvex surface, or combinations thereof. Preferably, the bottom surface260 is tapered in the shape of a funnel. The ratio of the maximum areaof the flow section over the minimum area of the flow section between adownwardly sloping bottom surface 260 of the chamber lid 232 and thesurface of the substrate 210 is preferably less than about 2, morepreferably less than about 1.5, more preferably less than about 1.3, andmost preferably about 1.

Not wishing to be bound by theory, it is believed that a gas having anuniform velocity across the surface of the substrate 210 provides a moreuniform deposition of the gas on the substrate 210. It is believed thatthe velocity of the gas is directly proportional to the concentration ofthe gas, which is in turn, directly proportional to the deposition rateof the gas on the substrate surface. Thus, a higher velocity of a gas ata first area of the surface of the substrate versus a second area of thesurface of the substrate is believed to provide a higher deposition ofthe gas on the first area. Accordingly, it is believed that a chamberlid having a downwardly sloping bottom surface 260 provides a moreuniform deposition of the gas across the surface of the substratebecause the downwardly sloping bottom surface provides a more uniformvelocity and, thus, a more uniform concentration of the gas across thesurface of the substrate.

At least a section of the internal surface of the chamber lid 232,including the expanding channel 234 and the bottom surface 260, has asurface roughness (Ra μin) preferably between about 46 R_(a) and 62R_(a), preferably about 54 R_(a). In addition, an upper surface of thepurge ring 222 and an upper surface of the chamber liner 299 may have asurface roughness between about 46 R_(a) and 62 R_(a), preferably about54 R_(a). It is believed that these surface roughnesses increase theadhesion of deposited film onto these surfaces. Increased adhesion ofthe deposited film reduces the likelihood that the deposited film willflake off during processing of substrates and, thus, reduces thelikelihood of particle contamination of the substrates. In a preferredembodiment, the surface roughnesses are provided by electropolishing toprovide a mirror polished surface. A mirror polished surface helpsproduce a laminar flow of a gas thereon. In other less preferredembodiments, the surface roughness can by provided by texturing thesurface in a suitable lay.

Control of the chamber lid 232 temperature is important to prevent gasdecomposition, deposition, or condensation on the chamber lid 232.Accordingly, the chamber lid 232 may include cooling elements and/orheating elements depending on the particular gas being deliveredtherethrough. For example, water channels (not shown) may be formed inthe chamber lid 232 to cool the chamber lid 232. In another example,heating elements (not shown) may be embedded or may surround componentsof the chamber lid 232 to heat the chamber lid 232.

The chamber lid 232 may also include a chamber plate portion 270 and acap portion 272. The cap portion 272 may be maintained at onetemperature range and the plate portion 270 may be maintained at anothertemperature range. For example, the cap 272 may be heated using heatertape or any other heating device to prevent condensation of reactantgases while the plate portion 270 is maintained at ambient temperature.In another example, the cap 272 may be heated and the plate portion 270may be cooled with water channels formed therethrough (not shown) toprevent thermal decomposition of reactant gases.

The chamber lid 232 may be made of stainless steel, aluminum,nickel-plated aluminum, nickel, or other suitable materials compatiblewith the processing to be performed. In one embodiment, the cap portion272 comprises stainless steal and the chamber plate portion 270comprises aluminum. In one embodiment, the additional plate comprisesstainless steal. In one embodiment, the expanding channel 234 and thebottom surface 260 of the chamber lid 232 may comprise a mirror polishedsurface to help produce a laminar flow of a gas along the expandingchannel 234 and the bottom surface 260 of the chamber lid 232. Inanother embodiment, the inner surface of the gas conduits 250A, 250B maybe electropolished to help produce a laminar flow of a gas therethrough.

The chamber lid 232 may further include a choke 262 disposed at aperipheral portion of the chamber lid 232, adjacent the periphery of thesubstrate 210. The choke 262 may be any type of obstruction capable ofrestricting the flow of gas within the reaction zone 264 at an areaadjacent the periphery of the substrate 210. The choke 262 helpsmaintain a substantially uniform pressure within the reaction zone 264.

For example, FIG. 2A shows a schematic cross-sectional view of oneembodiment of the choke 262. In this embodiment, the choke 262 includesa circumferential lateral portion 267. In one aspect, the purge ring 222may be adapted to direct a purge gas toward the lateral portion 267 ofthe choke 262.

As another example, FIG. 2B shows a schematic cross-sectional view ofanother embodiment of the choke 262. The choke 262 includes acircumferential downwardly extending protrusion 268. In one aspect, thepurge ring 222 may be adapted to direct a purge gas toward thecircumferential downwardly extending protrusion 268. In one aspect, thethickness of the downwardly extending protrusion 268 is between about0.01 inches and about 1.0 inch, more preferably 0.01 inches and 0.5inches.

The spacing between the choke 262 and the substrate support 212 istypically between about 0.04 inches and about 2.0 inches, and preferablybetween 0.04 inches and about 0.2 inches. The spacing may vary dependingon the gases being delivered and the process conditions duringdeposition. The choke 262 helps provide a more uniform pressuredistribution within the volume of a reaction zone 264 defined betweenthe chamber lid 232 and the substrate 210 by isolating the reaction zone264 from the non-uniform pressure distribution of the pumping zone 266(FIG. 1).

The gas delivery system 230 further includes one or more valves (fourare shown 242A, 242B, 252A, 252B) in fluid communication with separategas sources. Each valve 242A, 242B includes a delivery line 243A, 243Bhaving a valve seat assembly 244A, 244B and each valve 252A, 252Bincludes a purge line 245A, 245B having a valve seat assembly 246A,246B. Each delivery line 243A, 243B is in communication with arespective reactant gas source 238, 239 and in communication with arespective gas inlet 236A, 236B of the expanding channel 234. The valveseat assembly 244A, 244B of the delivery line 243A, 243B controls theflow of the reactant gas from the reactant gas source 238, 239 to theexpanding channel 234. The purge line 245A, 245B is in communicationwith the purge gas source 240 and intersects the delivery line 243A,243B downstream of the valve seat assembly 244A, 244B of the deliveryline 243A, 243B. The valve seat assembly 246A, 246B of the purge line245A, 245B controls the flow of the purge gas from the purge gas source240 to the delivery line 243A, 243B. If a carrier gas is used to deliverreactant gases from the reactant gas source 238, 239, preferably thesame gas is used as a carrier gas and a purge gas (i.e. an argon gasused as a carrier gas and a purge gas).

Programmable logic controllers 248A, 248B may be coupled to the valves242A, 242B to control actuation of the diaphragms of the valve seatassemblies 244A, 244B, 246A, 246B. Pneumatically actuated valves mayprovide pulses of gas in time periods as low as about 0.020 seconds.Electrically actuated valves may provide pulses of gas in time periodsas low as about 0.005 seconds. An electrically actuated valve typicallyrequires the use of a driver coupled between the valve and theprogrammable logic controller.

Each valve 242A, 242B may be a zero dead volume valve to enable flushingof a reactant gas from the delivery line 243A, 243B when the valve seatassembly 244A, 244B of the valve is closed. When the valve seat assembly244A, 244B is closed, the purge line 245A, 245B may provide a purge gasto flush the delivery line 243A, 243B. The purge line 245A, 245B may bepositioned adjacent the valve seat assembly 244A, 244B of the deliveryline 243A, 243B. Alternatively, the purge line 245A, 245B is positionedslightly spaced from the valve seat assembly 244A, 244B of the deliveryline 243A, 243B, as shown, so that a purge gas is not directly deliveredinto the valve seat assembly 244A, 244B when open. A zero dead volumevalve as used herein is defined as a valve which has negligible deadvolume (i.e. not necessarily zero dead volume.)

Each valve 242A, 242B may be adapted to provide a combined gas flowand/or separate gas flows of the reactant gas 238, 239 and the purge gas240. In reference to valve 242A, one example of a combined gas flow ofthe reactant gas 238 and the purge gas 240 provided by valve 242Acomprises a continuous flow of a purge gas from the purge gas source 240through purge line 245A and pulses of a reactant gas from the reactantgas source 238 through delivery line 243A. The continuous flow of thepurge gas may be provided by leaving the diaphragm of the valve seatassembly 246A of the purge line 245A open. The pulses of the reactantgas from the reactant gas source 238 may be provided by opening andclosing the diaphragm of the valve seat 244A of the delivery line 243A.In reference to valve 242A, one example of separate gas flows of thereactant gas 238 and the purge gas 240 provided by valve 242A comprisespulses of a purge gas from the purge gas source 240 through purge line245A and pulses of a reactant gas from the reactant gas source 238through delivery line 243A. The pulses of the purge gas may be providedby opening and closing the diaphragm of the valve seat assembly 246A ofthe valve 252A. The pulses of the reactant gas from the reactant gassource 238 may be provided by opening and closing the diaphragm of thevalve seat 244A of the valve 242A.

FIG. 3 shows an alternative embodiment of the gas delivery system 230having the valves 242A, 242B mounted below the chamber body 202 andcoupled to one or more gas lines 255 plumbed through the chamber body202. The gas lines 255 are in turn coupled to the gas conduits 250A,250B. The valves 242A, 242B may also be mounted in other positions andto other chamber components, such as on the chamber lid 232.

In one aspect, the valves 242A, 242B are coupled to separate reactantsources 238, 239 and separate purge gas sources 240, 241. Separate purgegas sources reduce the likelihood of cross-talk between the valves 242A,242B. In other embodiments, valves 242A and 242B may be coupled to thesame purge gas source 240, 241, as described above.

FIG. 4 shows a schematic, cross sectional view of the valves 242A, 242B,252A, 252B. Each valve includes a body 110 having three ports, areactant inlet 112, a purge inlet 114, and an outlet 116 in fluidcommunication. As described above, the reactant inlet 112 is in fluidcommunication with a reactant source 238, 239. The purge inlet 114 is influid communication with a purge gas source 240, 241, and the outlet 116is in fluid communication with the processing chamber 200.

FIG. 5 shows a schematic perspective view of the valve shown in FIG. 4.The valve body 110 may include one or more holes 510 for insertion of anembedded heating element 511. Preferably, the holes 510 are proximate tothe reactant inlet 112 (shown in FIG. 4) so that the reactant is heatedto prevent condensation of the reactant within the valve 242A, 242B. Thevalve body 110 may also include one or more holes 520 for insertion of athermocouple device 521 to monitor the temperature of the valve body110. For example, a measured temperature may be used in a feedback loopto control electric current applied to the heating element 511 from apower supply, such that the valve body temperature can be maintained orcontrolled at a desired temperature or within a desired temperaturerange. The holes 510 and 520 may be positioned in close proximity,preferably at a distance of about 2.0 mm or less, to the reactant inlet112 to better provide heating of the reactant inlet and to bettermonitor the temperature of the reactant inlet 112. Preferably, each hole510 for an embedded heating element is disposed in a direction parallelto the plane of the inlets 112, 114 and the outlet 116 so that theembedded heating element may also provide a more uniform heating of theinlets 112, 114 and the outlet 116.

FIG. 6 shows a diaphragm 134 is mounted over a valve seat 120, withinthe valve chamber 111. The diaphragm 134 is a schematic cross-sectionalview of one embodiment of one of the valves 242A, 242B. However, thediaphragm is typically biased in a closed position, and is selectivelymoved between an open position (as shown) and a closed position. Thediaphragm 134 is attached to a stem 336 which extends through, and isslidably supported by a bonnet 332. The stem 336 selectively moves thediaphragm 134 between a closed position and an open position. A cylinder340 is fixed to the top of the bonnet 332 and houses a piston 342. Thetop of the stem 336 protrudes from the bonnet 332 and is attached to alower surface of the piston 342. A spring 344 rests between the bonnet332 and the lower surface of the piston 342 and urges the piston 342 andthe stem 336 upwardly. The cylinder 340 forms an actuation chamber 346between an upper surface of the piston 342 and the inner surface of thecylinder 340.

The diaphragm 134 may be actuated pneumatically or electronically.Preferably, the diaphragm is actuated pneumatically by controllingpressurized gas from a pressurized gas supply 150, such as air or othergas, to selectively move the diaphragm 134. Although the diaphragm 134is pneumatically actuated, an electronically controlled valve 152, suchas a solenoid valve, may be mounted or coupled to the cylinder 340 toselectively provide the pressurized gas from the pressurized gas supply150 through a gas line 151. Although an electronically controlled valve152 provides pressurized gas to the diaphragm assembly 130, the valves242A, 242B are pneumatically actuated valves since the diaphragms 134is, actuated pneumatically.

The diaphragm 134 may be biased open or closed and may be actuatedclosed or opened respectively. In an open position, the diaphragm 134allows the in flow of a reactant from the reactant inlet 112 and the inflow of a purge gas from the purge inlet 114 through the valve chamber111 to the outlet 116 and into the chamber body 202. In a closedposition, the diaphragm 134 is in contact with the valve seat 120 toprevent in flow of a reactant from the reactant inlet 112 through thevalve chamber 111. In certain preferred embodiments, in a closedposition, the diaphragm 134 does not block the in flow of the purge gasfrom the purge inlet 114 through the valve chamber 111 to the outlet 116and into the chamber body 202. The valve chamber 111 may furthercomprise a groove 122 formed in the valve body 110 below the valve seat120 so that the purge inlet 114 and the outlet 116 remain in fluidcommunication whether the diaphragm 134 is in a closed position or openposition. As shown, the groove 122 is annular in shape, but may be anysuitable shape.

The valve seat 120 may be an integral piece with the valve body 110. Inan alternative embodiment, the valve seat 120 may be a separate piecefrom the valve body 110. The valve seat 120 is preferably made of achemically resistant material which does not react with the reactantprovided through the reactant inlet 112. Examples of chemicallyresistant material include polyimide (PI), polytetrafluoroethylene(PTFE), polychlorotriflouroethylene (PCTFE), perfluoroalkoxy (PFA), andother suitable polymers. In less preferred embodiments, the valve seat120 may be made of metals, metal alloys, and other suitable materials.In certain embodiments, depending on the reactant provided therethough,the valve body 110 is heated to a temperature between about 80° C. andabout 90C. to prevent condensation of the reactant on the diaphragm 134or other valve 242A, 242B components. If ammonia gas is used as areactant, the valve seat 120 is preferably made of a chemicallyresistant polyimide, such as VESPEL® CR-6100. It has been shown thatammonia gas is chemically inert with the polyimide VESPEL® CR-6100 attemperatures of 80° C. or above while ammonia gas may react with otherpolyimides at temperatures of 80° C. or above.

Regarding the operation of the valves 242A, 242B, programmable logiccontrollers (PLC) 248A, 248B are coupled to the valves 242A, 242B tocontrol electrical signals to the electronically controlled valve 152.The electronically controlled valve 152, when open, supplies pressurizedgas through the connector 349 into the actuation chamber 346 creating apressure that forces the piston 342 and the stem 336 downward againstthe elastic force of spring 344. The center portion of the diaphragm 134is pressed downward by stem 336 and comes into contact with the valveseat 120 closing the inflow of reactant from the reactant inlet 112 tothe outlet 116. When the diaphragm 134 is in contact with the valve seat120, the diaphragm 134 does not block off the groove 122 and a purge gasmay flow from the purge gas inlet 114 to the outlet 116. Theelectronically controlled valve 152, when closed, stops the supply ofpressurized gas and releases the pressurized gas inside the actuationchamber 346. When the supply of pressurized gas is stopped and pressureinside the actuation chamber 346 is released, the piston 342 and thestem 336 are raised by the elastic force of the spring 344. As thepiston 342 and the stem 336 rise, the diaphragm 134 moves away from thevalve seat 120 of the valve body 110 allowing the inflow of reactantfrom the reactant inlet 112 to the outlet 116.

The diaphragm 134 is moved between an open position and a closedposition to provide pulses of a reactant to the outlet 116 and into thechamber body 202. Since the diaphragm 134 in a closed position does notblock off the groove 122, a continuous flow of purge gas may be providedfrom the purge inlet 114 through the valve chamber 111 and out to theoutlet 116. As a consequence, the pulses of reactant may be dosed intothe continuous flow of purge gas provided through the valve chamber 111.The continuous flow of purge gas provided through the valve chamber 111flushes residual reactant remaining in the valve chamber 111 betweenpulses of reactants. In one aspect, each of the valves 242A, 242B has azero dead volume since there is negligible dead volume between the flowpath of the purge gas through the valve body 110 to the valve seat 120of the reactant inlet 112.

FIG. 7 is a graph of a diaphragm, such as a diaphragm 134 of one of thevalves 242A or 242B, moved between a closed position and an openposition. The term “response time” as used herein is defined as the timeto move the diaphragm of a valve from an open position to a closedposition or from a closed position to an open position. The responsetime to move the diaphragm of a valve from an open position to a closedposition and the response time to move the diaphragm of a valve from aclosed position to an open position may be the same or may be different,but are preferably approximately the same. Preferably, valves 242A, 242Bhave a response time of about 50 msec or less, more preferably 20 msecor less. It has been observed that a valve, such as valve 242A or 242B,with an internal volume of the actuation chamber of about 2.8 cm³ has aresponse time of about 40 msec or less. It has been observed that avalve, such as valve 242A or 242B, with an internal volume of theactuation chamber of about 0.9 cm³ has a response time of about 15 msecor less.

Reducing the response time of a valve assembly permits more cycles ofpulses of reactants to be provided over time. Therefore, throughput ofprocessing substrates is increased. However, the valves 242A, 242B canbe operated to any desired pulse time 720. The term “pulse time” as usedherein is defined as the time to move a diaphragm from a fully closedposition to a fully open position and back to the fully closed position.The valves 242A, 242B may be operated to provide pulse times of about1.0 second or less, about 500 msec or less, and even about 200 msec orless.

Pneumatic control of the diaphragm 134 provides a “soft” landing of thediaphragm 134 against the valve seat 120 in comparison to diaphragmsdriven up and down by a solenoid. The “soft” landing reduces theformation of particles during movement of the diaphragm between anopened position and a closed position caused by the impact of thediaphragm 134 against the valve seat 120. The “soft” landing alsoprovides the reactant through the valve assembly 100 in more of alaminar flow in comparison to a “hard” landing caused by moving thediaphragm directly by a solenoid.

In certain embodiments, the internal volume of the actuation chamber 346comprises a small volume, preferably about 3.0 cm³ or less, morepreferably about 1.0 cm³ or less. The term “internal volume of theactuation chamber” as used herein refers to the inner volume of theactuation chamber when the pressure inside the actuation chamber isreleased and includes the inner volume of the connector 349 and any gaslines between the actuation chamber 346 and the electrically controlledvalve 152. A small internal volume of the actuation chamber 346 can bepressurized more rapidly and as a consequence can actuate the diaphragm134 more rapidly.

The electronically controlled valve 152 is mounted to the cylinder 340of the diaphragm assembly 130 to reduce the added volume of a gas lineto the internal volume of the actuation chamber. An added volume of agas line will increase the internal volume of the actuation chamber andwill, thus, increase the time required to pressurize the actuationchamber 346 and, thus, will increase the response time of the valve242A, 242B. In alternative embodiments, if a gas line is used to couplethe electronically controlled valve 152 to the cylinder 340 of thediaphragm assembly 130 the length of the gas line is preferably about1.0 inch or less to reduce the internal volume of the actuation chamber.

The gas line 151 connecting the pressurized gas supply 150 to theelectronically controlled valve 152 preferably has an inner diameter ofgreater than about 0.125 inches, more preferably about 0.25 inches ormore. The larger inner diameter of the gas line 151 facilitates thefilling of the internal volume of the actuation chamber 346 by providinga greater conductance of pressurized gas therethrough. As a consequence,a larger inner diameter of the gas line 151 supplying pressurized gas tothe electronically controlled valve 152 reduces the response time of thevalve assembly 242A, 242B.

Referring again to FIG. 1, the valves 242A, 242B are in fluidcommunication with the expanding channel 234 via gas inlets 236B, thatare coupled to the delivery lines 243B. In one aspect, the gas inlets236A, 236B are located adjacent the upper portion 237 of the expandingchannel 234. In another aspect, the gas inlets 236A, 236B are locatedalong the length of the expanding channel 234 between the upper portion237 and the lower portion 235. The delivery lines 243A, 243B of thevalves 242A, 242B may be coupled to the gas inlets 236A, 236B throughgas conduits 250A, 250B. The gas conduits 250A, 250B may be integratedor may be separate from the valves 242A, 242B. In one aspect, the valves242A, 242B are coupled in close proximity to the expanding channel 234to reduce any unnecessary volume of the delivery line 243A, 243B and thegas conduits 250A, 250B between the valves 242A, 242B and the gas inlets236A, 236B.

The expanding channel 234 has an inner diameter that increases from anupper portion 237 to a lower portion 235 thereof. In one specificembodiment, the inner diameter of the expanding channel 234 for achamber adapted to process 200 mm diameter substrates is between about0.2 inches about 1.0 inches, more preferably between about 0.3 and about0.9 inches, and more preferably between 0.3 inches and about 0.5 at theupper portion 237 of the expanding channel 234 and between about 0.5inches and about 3.0 inches, preferably between about 0.75 inches andabout 2.5 inches, and more preferably between about 1.1 inches and about2.0 inches at the lower portion 235 of the expanding channel 234 Inanother specific embodiment, the inner diameter of the expanding channel234 for a chamber adapted to process 300 mm diameter substrates isbetween about 0.2 inches about 1.0 inches, more preferably between about0.3 and about 0.9 inches, and more preferably between 0.3 inches andabout 0.5 at the upper portion 237 of the expanding channel 234 andbetween about 0.5 inches and about 3.0 inches, preferably between about0.75 inches and about 2.5 inches, and more preferably between about 1.2inches and about 2.2 inches at the lower portion 235 of the expandingchannel 234 for a 300 mm substrate. In general, the above dimensionsapply to an expanding channel adapted to provide a total gas flow ofbetween about 500 sccm and about 3,000 sccm. However, the dimensions maybe altered to accommodate any gas flow therethough.

The expanding channel 234 may be shaped as a truncated cone (includingshapes resembling a truncated cone). Whether a gas is provided towardthe walls of the expanding channel 234 or directly downward towards thesubstrate 210, the velocity of the gas flow decreases as the gas flowtravels through the expanding channel 234 due to the expansion of thegas. The reduction of the velocity of the gas flow helps reduce thelikelihood of the gas blowing off reactants adsorbed on the surface ofthe substrate 210.

Not wishing to be bound by theory, it is believed that the diameter ofthe expanding channel 234, which is gradually increasing from the upperportion 237 to the lower portion 235, allows less of an adiabaticexpansion of a gas flowing through the expanding channel 234 which helpsto control the temperature of the gas. A sudden adiabatic expansion of agas flowing through the expanding channel 234 may decrease thetemperature of the gas resulting in condensation of the gas andformation of particles. Creating less of an adiabatic expansion of agas, more heat may be transferred to or from the gas and thus, thetemperature of the gas may be more easily controlled. The graduallyexpanding channel may comprise one or more tapered inner surfaces, suchas a tapered straight surface, a concave surface, a convex surface, orcombinations thereof or may comprise sections of one or more taperedinner surfaces (i.e. a portion tapered and a portion non-tapered).

FIG. 8 is a top cross-sectional view of one embodiment of the expandingsection 234 of the chamber lid 232. Each gas conduit 250A, 250B may bepositioned at an angle a from the center line 302 of the gas conduit250A, 250B and from a radius line 304 from the center of the expandingchannel 234. Entry of a gas through the gas conduit 250A, 250Bpreferably positioned at an angle α (i.e., when α>0°) causes the gas toflow in a circular direction as shown by arrow 310A (or 310B). Providinggas at an angle a as opposed to directly straight-on to the walls of theexpanding channel (i.e. when α=0°) helps to provide a more laminar flowthrough the expanding channel 234 rather than a turbulent flow. It isbelieved that a laminar flow through the expanding channel 234 resultsin an improved purging of the inner surface of the expanding channel 234and other surfaces of the chamber lid 232. In comparison, a turbulentflow may not uniformly flow across the inner surface of the expandingchannel 234 and other surfaces and may contain dead spots or stagnantspots in which there is no gas flow. In one aspect, the gas conduits250A, 250B and the corresponding gas inlets 236A, 236B are spaced outfrom each other and direct a flow in the same circular direction (i.e.,clockwise or counter-clockwise).

FIG. 9 is a top cross-sectional view of another embodiment of theexpanding channel of the chamber lid which is adapted to receive asingle gas flow through one gas inlet 636 from one gas conduit 650coupled to a single or a plurality of valves (not shown). The gasconduit 650 may be positioned at an angle a from the center line 602 ofthe gas conduit 650 and from a radius line 604 from the center of theexpanding channel 634. The gas conduit 650 positioned at an angleα(i.e., when α>0°) causes a gas to flow in a circular direction as shownby arrow 610.

FIG. 10 is a top cross-sectional view of another embodiment of theexpanding channel of the chamber lid which is adapted to receive threegas flows together, partially together (i.e. two of three gas flowstogether), or separately through three gas inlets 736A, 736B, 736C fromthree gas conduits 750A, 750B, 750C in which each conduit is coupled toa single or a plurality of valves (not shown). The gas conduits 750A,750B, 750C may be positioned at an angle a from the center line 702 ofthe gas conduits 750A, 750B, 750C and from a radius line 704 from thecenter of the expanding channel 734. The gas conduits 750A, 750B, 750Cpositioned at an angle a (i.e., when α>0°) causes a gas to flow in acircular direction as shown by arrow 710.

FIG. 11 shows a cross-sectional view of the expanding channel 234showing a simplified representation of two gas flows therethrough. Eachgas conduit 250A, 250B and gas inlet 236A, 236B may be positioned in anyrelationship to a longitudinal axis 290 of the expanding channel. Eachgas conduit 250A, 250B and gas inlet 236A, 236B are preferablypositioned normal (in which +B, −B=to 90°) to the longitudinal axis 290or positioned at an angle +B or an angle −B (in which 0° <+B <90° or0°<−B <90°) from the centerline 302A, 302B of the gas conduit 250A, 250Bto the longitudinal axis 290. Therefore, the gas conduit 250A, 250B maybe positioned horizontally normal to the longitudinal axis 290 as shownin FIG. 3, may be angled downwardly at an angle +B, or may be angledupwardly at an angle −B to provide a gas flow toward the walls of theexpanding channel 234 rather than directly downward towards thesubstrate 210 which helps reduce the likelihood of blowing off reactantsabsorbed on the surface of the substrate 210. In addition, the diameterof the gas conduits 250A, 250B may be increasing from the delivery lines243A, 243B of the valves 242A, 242B to the gas inlet 236A, 236B to helpreduce the velocity of the gas flow prior to its entry into theexpanding channel 234. For example, the gas conduits 250A, 250B maycomprise an inner diameter which is gradually increasing or may comprisea plurality of connected conduits having increasing inner diameters.

Although the exact flow pattern through the expanding channel 234 is notknown, it is believed that the circular flow 310 may travel as a“vortex” or “spiral” flow 402A, 402B through the expanding channel 234as shown by arrows 402A, 402B. In one aspect, the vortex flow may helpto establish a more efficient purge of the expanding channel 234 due tothe sweeping action of the vortex flow pattern across the inner surfaceof the expanding channel 234.

In one embodiment, the distance 410 between the gas inlets 236A, 236Band the substrate 210 is made far enough that the “vortex” flow 402dissipates to a downwardly flow as shown by arrows 404 as a spiral flowacross the surface of the substrate 210 may not be desirable. It isbelieved that the “vortex” flow 402 and the downwardly flow 404 proceedsin a laminar manner efficiently purging the chamber lid 232 and thesubstrate 210. In one specific embodiment the distance 410 between theupper portion 237 of the expanding channel 234 and the substrate 210 isabout 1.0 inches or more, more preferably about 2.0 inches or more. Inone specific embodiment, the upper limit of the distance 410 is dictatedby practical limitations. For example, if the distance 410 is very long,then the residence time of a gas traveling though the expanding channel234 would be long, then the time for a gas to deposit onto the substratewould be long, and then throughput would be low. In addition, ifdistance 410 is very long, manufacturing of the expanding channel 234would be difficult. In general, the upper limit of distance 410 may be 3inches or more for a chamber adapted to process 200 mm diametersubstrates or 5 inches or more for a chamber adapted to process 300 mmdiameter substrates.

FIG. 12 shows a schematic view illustrating the flow of a gas at twodifferent positions 502, 504 between the bottom surface 260 of thechamber lid 232 and the surface of a substrate 210. The velocity of thegas at any flow section, i.e. at any radius, is theoretically determinedby the equation below:Q/A=V  (1)“Q” is the flow of the gas. “A” is the area of the flow section. “V” isthe velocity of the gas. The velocity of the gas is inverselyproportional to the area of the flow section (H×2π R ), in which “H” isthe height of the flow section and “2π R” is the circumference of theflow section. In other words, the velocity of a gas is inverselyproportional to the height “H” of the flow section and the radius “R” ofthe flow section.

Comparing the velocity of the flow section at position 502 and position504, assuming that the flow “Q” of the gas at all positions between thebottom surface 260 of the chamber lid 232 and the surface of thesubstrate 210 is equal, the velocity of the gas may be theoreticallymade equal by having the area “A” of the flow sections equal. For thearea of flow sections at position 502 and position 504 to be equal, theheight H₁ at position 502 must be greater than the height H₂ since R₂>R₁.

In operation, a substrate 210 is delivered to the chamber 200 throughthe opening 208 by a robot (not shown). The substrate 210 is positionedon the substrate support 212 through cooperation of the lift pins 220and the robot. The substrate support 212 raises the substrate 210 intoclose opposition to the bottom surface 260 of the chamber lid 232. Afirst gas flow may be injected into the expanding channel 234 of thechamber 200 by valve 242A together or separately (i.e. pulses) with asecond gas flow injected into the chamber 200 by valve 242B. The firstgas flow may comprise a continuous flow of a purge gas from purge gassource 240 and pulses of a reactant gas from reactant gas source 238 ormay comprise pulses of a reactant gas from reactant gas source 238 andpulses of a purge gas from purge gas source 240. The second gas flow maycomprises a continuous flow of a purge gas from purge gas source 240 andpulses of a reactant gas from reactant gas source 239 or may comprisepulses of a reactant gas from reactant gas source 239 and pulses of apurge gas from purge gas source 240. The gas flow travels through theexpanding channel 234 as a vortex flow pattern 402 which provides asweeping action across the inner surface of the expanding channel 234.The vortex flow pattern 402 dissipates to a downwardly flow 404 towardthe surface of the substrate 210. The velocity of the gas flow reducesas it travels through the expanding channel 234. The gas flow thentravels across the surface of the substrate 210 and across the bottomsurface 260 of the chamber lid 232. The bottom surface 260 of thechamber lid 232, which is downwardly sloping, helps reduce the variationof the velocity of the gas flow across the surface of the substrate 210.The gas flow then travels by the choke 262 and into the pumping zone 266of the chamber 200. Excess gas, by-products, etc. flow into the pumpingchannel 279 and are then exhausted from the chamber 200 by the vacuumsystem 278. In one aspect, the gas flow proceeds through the expandingchannel 234 and between the surface of the substrate 210 and the bottomsurface 260 of the chamber lid 232 in a laminar manner which aids inuniform exposure of a reactant gas to the surface of the substrate 210and efficient purging of inner surfaces of the chamber lid 232.

FIGS. 13 and 14 illustrate alternative embodiments of a gas deliverysystem capable of performing atomic layer deposition according to thepresent invention. Since some components are the same or similar tothose described above, like numbers have been used where appropriate.

More particularly, FIG. 13 shows a chamber 800 having a gas deliveryapparatus 830 comprising a chamber lid 832 that has a substanticallyflat bottom surface 860. In one aspect, the spacing between the choke262 and the substrate support 210 is between about 0.04 inches and about2.0 inches, more preferably between about 0.04 inches and about 0.2inches.

FIG. 14 shows a chamber 900 having a gas delivery apparatus 930comprising a chamber lid 932 that provides a reaction zone 964 having asmall volume and that provides a downwardly sloping or funnel shapedbottom surface 960. Gas sources 937 are coupled to the passageway 933through one or more valves 941. In one aspect, the passageway 933 has along length to reduce the likelihood that a gas introduced through valve941 will blow off reactants absorbed on the surface of the substrate210.

FIG. 15 is a schematic view of one embodiment of a gas box 1000 usefulwith the present invention. For clarity and ease of description, the gasbox 1000 will be described with reference to the chamber 200 shown inFIG. 3. The gas box 1000 provides one or more compounds to the valves242A, 242B. The gas box 1000 may be a single or a plurality of gas boxsections (two are shown 1000A, 1000B). Each gas box section 1000A, 1000Bmay also include a connection 1010 to a respective purge gas source 240,241. The gas box sections 1000A, 1000B may further include variousvalves for regulating or otherwise controlling the compounds provided tothe valves 242A, 242B.

FIG. 16 is a schematic cross-sectional view of one embodiment of thecanister 1300 for generating a gas via sublimation from a solid reactantsource, such as PDMAT. The canister 1330 may be adapted to provide a gasfrom a liquid reactant source. In general, the canister 1330 includes asidewall 1202, a lid 1204 and a bottom 1232 enclosing an interior volume1238. At least one of the lid 1204 or sidewall 1202 contains an inletport 1206 and an outlet port 1208 for gas entry and egress. Inlet andoutlet ports 1206, 1208 are coupled to valves 1112, 1114 fitted withmating disconnect fittings 1236A, 1236B to facilitate removal of thecanister 1300 from the gas delivery system 230. Optionally, an oil trap1250 is coupled between the outlet port 1208 and the valve 1114 tocapture any oil particulate that may be present in the gas flowing tothe process chamber 200.

The interior volume 1238 of the canister 1300 is split into an upperregion 1218 and a lower region 1234. Source solids 1214 at leastpartially fill the lower region 1234. A tube 1302 is disposed in theinterior volume 1238 of the canister 1300 and is adapted to direct aflow of gas within the canister 1300 away from the source solids 1214advantageously preventing gas flowing out of the tube 1302 from directlyimpinging the source solids 1214 and causing particulates to becomeairborne and carried through the outlet port 1208 and into theprocessing chamber 200.

The tube 1302 is coupled at a first end 1304 to the inlet port 1206. Thetube 1302 extends from the first end 1304 to a second end 1326A that ispositioned in the upper region 1218 above the source solids 1214. Thesecond end 1326A may be adapted to direct the flow of gas toward thesidewall 1202, thus preventing direct (linear) flow of the gas throughthe canister 1300 between the ports 1206, 1208, creating an extendedmean flow path.

In one embodiment, an outlet 1306 of the second end 1326A of the tube1302 is positioned at an angle of about 15 to about 90 degrees relativeto a center axis 1308 of the canister 1300. In another embodiment, thetube 1302 has a ‘J’-shaped second end 1326B that directs the flow of gasexiting the outlet 1306 towards the lid 1204 of the canister 1300. Inanother embodiment, the tube 1302 has a second end 1326C having a plugor cap 1310 closing the end of the tube 1302. The second end 1326C hasat least one opening 1328 formed in the side of the tube 1302 proximatethe cap 1310. Gas, exiting the openings 1328, is typically directedperpendicular to the center axis 1308 and away from the source solids1214 disposed in the lower region 1234 of the canister 1300. Optionally,an at least one baffle 1210 (shown in phantom) as described above may bedisposed within the chamber 1300 and utilized in tandem with any of theembodiments of the tube 1302 described above.

In operation, the lower region 1234 of the canister 1300 is at leastpartially filled with a source solid 1214. Alternatively, a liquid 1216may be added to the source solid 1214 to form a slurry 1212. Thecanister 1300 is held at a desired pressure and is heated to a desiredtemperature by a resistive heater 1230 located proximate to the canister1300. A carrier gas, such as argon gas, is flowed through the inlet port1206 and the tube 1302 into the upper region 1218 at a desired rate. Thesecond end 1326A of the tube 1302 directs the flow of the carrier gas inan extended mean flow path away from the outlet port 1208,advantageously increasing the mean dwell time of the carrier gas in theupper region 1218 of the canister 1300 and preventing direct flow ofcarrier gas upon the source solids 1214 to minimize particulategeneration. The increased dwell time in the canister 1300 advantageouslyincreases the saturation level of vapors of the sublimated solid withinthe carrier gas while the decrease in particulate generation improvesproduct yields, conserves source solids, and reduces downstreamcontamination.

Referring to FIG. 15, the temperature of various components of thechamber 200 and the gas box 1000 may be controlled to reduce unwantedparticle formation in the chamber. For example, controlling thetemperature may prevent gas decomposition, deposition, or condensationon various components of the chamber 200 and the gas box 1000. Forexample, it may be desirable that the flow paths of the reactants fromthe reactant source to the gas distribution system 230 are at arelatively high temperature to prevent condensation (i.e. vapor to solidor vapor to liquid) of the reactants in the flow path. It may bedesirable that the chamber body 202 and the chamber lid 232 are at arelatively low temperature to prevent deposition of the reactants on thesurfaces of the chamber body and the chamber lid.

In one embodiment, the canister 1300 is maintained at a temperaturebetween about 60° C. to about 70° C. The gas lines (denoted by area1330) from the canister 1300 to the valve 242A and from the canister1300 to the foreline are maintained, such as by heater tape or otherheating device, at a temperature between about 80° C. and about 90° C.The valve 242A is maintained at a temperature between about 80° C. andabout 90° C. The gas line 255 (denoted by area 1332) from the valve 242Ato the chamber body 202 is maintained, such as by heater tape or otherheating device, at a temperature between about 85° C. and about 95° C.Preferably, there is a slight increasing temperature gradient of theflow path of the reactant from the canister 1300 to the chamber body 202so that any condensation of the reactant will flow toward the canisterrather than toward the chamber body 202. In addition, the purge gassource 240 preferably provides a pre-heated purge gas, such as argongas, at a temperature between about 85° C. and about 95° C. Thepre-heated purge gas helps reduce the likelihood of particle formationat area 1332 due the expansion of gases at area 1332 due to theincreased volume at area 1332.

Then, gas line 255 (denoted by area 1334) from the chamber plate portion270 to the cap 272 is maintained, such as by a cartridge heater orheater tape, at a temperature between about 45° C. and about 55° C. Inother embodiments, area 1334 is not directly heated (i.e. there is noheating device directly controlling the temperature of area 1334).

In one embodiment, the gas lines from the purge gas source and thenitrogen containing source to the valve 242B are not heated. Valve 242Bis not heated. The gas line 255 from the valve 242B to the chamber body202 and the gas line 255 from the chamber plate portion 270 to the cap272 are also not heated.

In one embodiment, the chamber sidewalls 204 are maintained at atemperature between about 20° C. and about 25° C. The chamber plateportion 270 is maintained at a temperature between about 25° C. andabout 35° C. The cap 272 is maintained at a temperature between about30° C. and about 40° C. The chamber sidewall 202 may be maintained at adesired temperature by forming channels 295 (FIG. 1) therethrough andproviding a temperature control fluid, such as a cooling fluid orheating fluid, through the channels.

In one embodiment, the chamber plate portion 270 and the cap 272 do notinclude heating or cooling elements. Cooling of the chamber plateportion 270 and the cap 272 are provided by heat transfer from thechamber plate portion 270 and the cap 272 to the chamber sidewalls 204.In other embodiments, the chamber plate portion 270 and the cap 272 mayinclude cooling elements and/or heating elements. In one embodiment, thegas lines 255 plumbed through the chamber body 202 do not contact thechamber body 202 and/or are separated from the chamber body 202 by aninsulator which minimizes the heat transfer between the gas lines 255and the chamber body 202.

In certain embodiments, the valves 242A, 242B are mounted apart or awayfrom the chamber lid 232, such as below the chamber body 202 as shown inFIG. 3, to simplify control of the temperature of the chamber lid 232.For example, a heated valve mounted to or in close proximity to thechamber lid 232 may transfer heat to the chamber lid 232. Heattransferred to the chamber lid 232 may cause or increase unwanteddeposition of gases on the interior surfaces thereof, such as on theexpanding channel 234 and the bottom surface 260. The valves 242A, 242Bmounted away from the lid do not significantly increase the volume ofreaction zone 264 because there is little or no backstreaming of gasesinto the gas conduits 250A, 250B. For example, with a continuous flow ofa purge provided by the valves 242A, 242B with reactants dosed into thepurge gas stream, there is a substantially constant forward flow ofgases provided through the gas conduits 250A, 250B into the chamber body202.

The control unit 280, such as a programmed personal computer, workstation computer, or the like, may be coupled to the chamber 200 tocontrol processing conditions, as shown in FIG. 1. For example, thecontrol unit 280 may be configured to control flow of various processgases and purge gases from gas sources 238, 239, 240 through the valves242A, 242B during different stages of a substrate process sequence. Thecontrol unit 280 may include a central processing unit (CPU) 282,support circuitry 284, and memory 286 containing associated controlsoftware 283.

The control unit 280 may be one of any form of general purpose computerprocessor that can be used in an industrial setting for controllingvarious chambers and sub-processors. The CPU 282 may use any suitablememory 286, such as random access memory, read only memory, floppy diskdrive, hard disk, or any other form of digital storage, local or remote.Various support circuits may be coupled to the CPU 282 for supportingthe chamber 200. The control unit 280 may be coupled to anothercontroller that is located adjacent individual chamber components, suchas the programmable logic controllers 248A, 248B of the valves 242A,242B. Bi-directional communications between the control unit 280 andvarious other components of the chamber 200 are handled through numeroussignal cables collectively referred to as signal buses 288, some ofwhich are illustrated in FIG. 1. In addition to control of process gasesand purge gases from gas sources 238, 239, 240 and from the programmablelogic controllers 248A, 248B of the valves 242A, 242B, the control unit280 may be configured to be responsible for automated control of otheractivities used in wafer processing, such as wafer transport,temperature control, chamber evacuation, among other activities, some ofwhich are described elsewhere herein.

The processing chamber 200 and the gas delivery apparatus 230, describedabove may be used to advantage to implement cyclical deposition ofelements, which include but are not limited to, tantalum, titanium,tungsten, and copper, or to implement cyclical deposition of compoundsor alloys/combination films, which include but are not limited totantalum nitride, tantalum silicon nitride, titanium nitride, titaniumsilicon nitride, tungsten nitride, tungsten silicon nitride, and copperaluminum on a substrate surface. The processing chamber 200 and the gasdelivery apparatus 230, as described above, may also be used toadvantage to implement chemical vapor deposition of various materials ona substrate surface.

A “substrate surface”, as used herein, refers to any substrate surfaceupon which film processing is performed. For example, a substratesurface may include silicon, silicon oxide, doped silicon, germanium,gallium arsenide, glass, sapphire, and any other materials such asmetals, metal nitrides, metal alloys, and other conductive materials,depending on the application. A substrate surface may also includedielectric materials such as silicon dioxide and carbon doped siliconoxides.

“Cyclical deposition” as used herein refers to the sequentialintroduction of two or more reactive compounds to deposit a mono layerof material on a substrate surface. The two or more reactive compoundsare alternatively introduced into a reaction zone of a processingchamber. Each reactive compound is separated by a time delay to alloweach compound to adhere and/or react on the substrate surface. In oneaspect, a first precursor or compound A is pulsed into the reaction zonefollowed by a first time delay. Next, a second precursor or compound Bis pulsed into the reaction zone followed by a second delay. When aternary material is desired, such as titanium silicon nitride, forexample, a third compound (C), is dosed/pulsed into the reaction zonefollowed by a third time delay. During each time delay an inert gas,such as argon, is introduced into the processing chamber to purge thereaction zone or otherwise remove any residual reactive compound fromthe reaction zone. Alternatively, the purge gas may flow continuouslythroughout the deposition process so that only the purge gas flowsduring the time delay between pulses of reactive compounds. The reactivecompounds are alternatively pulsed until a desired film or filmthickness is formed on the substrate surface.

A “pulse” or “dose” as used herein is intended to refer to a quantity ofa particular compound that is intermittently or non-continuouslyintroduced into a reaction zone of a processing chamber. The quantity ofa particular compound within each pulse may vary over time, depending onthe duration of the pulse. The duration of each pulse is variabledepending upon a number of factors such as, for example, the volumecapacity of the process chamber employed, the vacuum system coupledthereto, and the volatility/reactivity of the particular compounditself.

The durations for each pulse/dose are variable and may be adjusted toaccommodate, for example, the volume capacity of the processing chamberas well as the capabilities of a vacuum system coupled thereto.Additionally, the dose time of a compound may vary according to the flowrate of the compound, the pressure of the compound, the temperature ofthe compound, the type of dosing valve, the type of control systememployed, as well as the ability of the compound to adsorb onto thesubstrate surface. Dose times may also vary based upon the type of layerbeing formed and the geometry of the device. In general, a dose timeshould be long enough to provide a volume of compound sufficient toadsorb/chemisorb onto substantially the entire surface of the substrateand form a layer of the desired thickness of the compound thereon.

The term “compound” is intended to include one or more precursors,oxidants, reductants, reactants, and catalysts, or a combinationthereof. The term “compound” is also intended to include a grouping ofcompounds, such as when two or more compounds are introduced in aprocessing system at the same time. For example, a grouping of compoundsmay include one or more catalysts and one or more precursors. The term“compound” is further intended to include one or more precursors,oxidants, reductants, reactants, and catalysts, or a combination thereofin an activated or otherwise energized state, such as by disassociationor ionization.

It is believed that the surface attraction used to physisorb, adsorb,absorb, or chemisorb a monolayer of reactants on a substrate surface areself-limiting in that only one monolayer may be deposited onto thesubstrate surface during a given pulse because the substrate surface hasa finite number of sites available for the reactants. Once the finitenumber of sites is occupied by the reactants, further deposition of thereactants will be blocked. The cycle may be repeated to a desiredthickness of the tantalum nitride layer.

For clarity and ease of description, the method will be furtherdescribed as it relates to the deposition of a tantalum nitride (TaN)barrier layer using a cyclical deposition technique. Pulses of atantalum containing compound, such as pentadimethylamino-tantalum(PDMAT; Ta(NMe₂)₅), may be introduced by gas source 238 through valve242A. The tantalum containing compound may be provided with the aid of acarrier gas, which includes, but is not limited to, helium (He), argon(Ar), nitrogen (N₂), hydrogen (H₂), and combinations thereof. Pulses ofa nitrogen containing compound, such as ammonia, may be introduced bygas source 239 through valve 242A. A carrier gas may also be used tohelp deliver the nitrogen containing compound. A purge gas, such asargon, may be introduced by gas source 240 through valve 242A and/orthrough valve 242B. In one aspect, the flow of purge gas may becontinuously provided by gas sources 240 through valves 242A, 242B toact as a purge gas between the pulses of the tantalum containingcompound and of the nitrogen containing compound and to act as a carriergas during the pulses of the tantalum containing compound and thenitrogen containing compound. In one aspect, delivering a purge gasthrough two gas conduits 250A, 250B provides a more complete purge ofthe reaction zone 264 rather than a purge gas provided through one gasconduit 250A, 250B. In one aspect, a reactant gas may be deliveredthrough one gas conduit 250A, 250B since uniformity of flow of areactant gas, such as a tantalum containing compound or a nitrogencontaining compound, is not as critical as uniformity of the purge gasdue to the self-limiting absorption process of the reactants on thesurface of substrate structures. In other embodiments, a purge gas maybe provided in pulses. In other embodiments, a purge gas may be providedin more or less than two gas flows. In other embodiments, a tantalumcontaining gas may be provided in more than a single gas flow (i.e. twoor more gas flows). In other embodiments, a nitrogen containing may beprovided in more than a single gas flow (i.e. two or more gas flows).

Other examples of tantalum containing compounds, include, but are notlimited to, other organo-metallic precursors or derivatives thereof,such as pentaethylmethylamino-tantalum (PEMAT; Ta[N(C₂H₅CH₃)₂]₅),pentadiethylaminotantalum (PDEAT; Ta(NEt₂)₅,), and any and allderivatives of PEMAT, PDEAT, or PDMAT. Other tantalum containingcompounds include without limitation TBTDET (Ta(NEt₂)₃NC₄H₉ orC₁₆H₃₉N₄Ta) and tantalum halides, for example TaX₅ where X is fluorine(F), bromine (Br) or chlorine (Cl), and/or derivatives thereof. Othernitrogen containing compounds may be used which include, but are notlimited to, N_(x)H_(y) with x and y being integers (e.g., hydrazine(N₂H₄)), dimethyl hydrazine ((CH₃)₂N2H2), t-butylhydrazine (C₄H₉N₂H₃)phenylhydrazine (C₆H₅N₂H₃), other hydrazine derivatives, a nitrogenplasma source (e.g., N₂, N₂/H₂, NH₃, or a N₂H₄ plasma),2,2′-azoisobutane ((CH₃)₆C₂N₂), ethylazide (C₂H₅N₃), and other suitablegases. Other examples of purge gases include, but are not limited to,helium (He), nitrogen (N₂), hydrogen (H₂), other gases, and combinationsthereof.

The tantalum nitride layer formation is described as starting with theadsorption of a monolayer of a tantalum containing compound on thesubstrate followed by a monolayer of a nitrogen containing compound.Alternatively, the tantalum nitride layer formation may start with theadsorption of a monolayer of a nitrogen containing compound on thesubstrate followed by a monolayer of the tantalum containing compound.Furthermore, in other embodiments, a pump evacuation alone betweenpulses of reactant gases may be used to prevent mixing of the reactantgases.

The time duration for each pulse of the tantalum containing compound,the time duration for each pulse of the nitrogen containing compound,and the duration of the purge gas between pulses of the reactants arevariable and depend on the volume capacity of a deposition chamberemployed as well as a vacuum system coupled thereto. For example, (1) alower chamber pressure of a gas will require a longer pulse time; (2) alower gas flow rate will require a longer time for chamber pressure torise and stabilize requiring a longer pulse time; and (3) a large-volumechamber will take longer to fill, longer for chamber pressure tostabilize thus requiring a longer pulse time. Similarly, time betweeneach pulse is also variable and depends on volume capacity of theprocess chamber as well as the vacuum system coupled thereto. Ingeneral, the time duration of a pulse of the tantalum containingcompound or the nitrogen containing compound should be long enough foradsorption of a monolayer of the compound. In one aspect, a pulse of atantalum containing compound may still be in the chamber when a pulse ofa nitrogen containing compound enters. In general, the duration of thepurge gas and/or pump evacuation should be long enough to prevent thepulses of the tantalum containing compound and the nitrogen containingcompound from mixing together in the reaction zone.

Generally, a pulse time of about 1.0 second or less for a tantalumcontaining compound and a pulse time of about 1.0 second or less for anitrogen containing compound are typically sufficient to absorbalternating monolayers on a substrate structure. A time of about 1.0second or less between pulses of the tantalum containing compound andthe nitrogen containing compound is typically sufficient for the purgegas, whether a continuous purge gas or a pulse of a purge gas, toprevent the pulses of the tantalum containing compound and the nitrogencontaining compound from mixing together in the reaction zone. Ofcourse, a longer pulse time of the reactants may be used to ensureabsorption of the tantalum containing compound and the nitrogencontaining compound and a longer time between pulses of the reactantsmay be used to ensure removal of the reaction by-products.

During deposition, the substrate 210 may be maintained approximatelybelow a thermal decomposition temperature of a selected tantalumcontaining compound. An exemplary heater temperature range to be usedwith tantalum containing compounds identified herein is approximatelybetween about 20° C. and about 500° C. at a chamber pressure less thanabout 100 torr, preferably less than 50 torr. When the tantalumcontaining gas is PDMAT, the heater temperature is preferably betweenabout 100° C. and about 300° C., more preferably between about 175° C.and 250° C., and the chamber pressure is between about 1.0 and about 5.0torr. In other embodiments, it should be understood that othertemperatures and pressures may be used. For example, a temperature abovea thermal decomposition temperature may be used. However, thetemperature should be selected so that more than 50 percent of thedeposition activity is by absorption processes. In another example, atemperature above a thermal decomposition temperature may be used inwhich the amount of decomposition during each precursor deposition islimited so that the growth mode will be similar to an atomic layerdeposition growth mode.

An exemplary process of depositing a tantalum nitride layer by cyclicaldeposition, comprises providing pulses of pentadimethylamino-tantalum(PDMAT) from gas source 238 at a flow rate between about 100 sccm andabout 1000 sccm, preferably between about 100 sccm and about 400 sccm,through valve 242A for a pulse time of about 0.5 seconds or less, about0.1 seconds or less, or about 0.05 seconds or less due the smallervolume of the reaction zone 264. Pulses of ammonia may be provided fromgas source 239 at a flow rate between about 100 sccm and about 1000sccm, preferably between 200 sccm and about 600 sccm, through valve 242Bfor a pulse time of about 0.5 seconds or less, about 0.1 seconds orless, or about 0.05 seconds or less due to a smaller volume of thereaction zone 264. An argon purge gas at a flow rate between about 100sccm and about 1000 sccm, preferably, between about 100 sccm and about400 sccm, may be continuously provided from gas source 240 throughvalves 242A, 242B. The time between pulses of the tantalum containingcompound and the nitrogen containing compound may be about 0.5 secondsor less, about 0.1 seconds or less, or about 0.07 seconds or less due tothe smaller volume of the reaction zone 264. It is believed that a pulsetime of about 0.016 seconds or more is required to fill the reactionzone 264 with a reactant gas and/or a purge gas. The heater temperaturepreferably is maintained between about 100° C. and about 300° C. at achamber pressure between about 1.0 and about 5.0 torr. This processprovides a tantalum nitride layer in a thickness between about 0.5 Å andabout 1.0 Å per cycle. The alternating sequence may be repeated until adesired thickness is achieved.

In one embodiment, the layer, such as a tantalum nitride layer, isdeposited to a sidewall coverage of about 50 Å or less. In anotherembodiment, the layer is deposited to a sidewall coverage of about 20 Åor less. In still another embodiment, the layer is deposited to asidewall coverage of about 10 Å or less. A tantalum nitride layer with athickness of about 10 Å or less is believed to be a sufficient thicknessin the application as a barrier layer to prevent copper diffusion. Inone aspect, a thin barrier layer may be used to advantage in fillingsub-micron (e.g., less than 0.15 μm) and smaller features having highaspect ratios (e.g., greater than 5 to 1). Of course, a layer having asidewall coverage of greater than 50 Å may be used.

Embodiments of cyclical deposition have been described above asabsorption of a monolayer of reactants on a substrate. The presentinvention also includes embodiments in which the reactants are depositedto more or less than a monolayer. The present invention also includesembodiments in which the reactants are not deposited in a self-limitingmanner. The present invention also includes embodiments in whichdeposition occurs in mainly a chemical vapor deposition process in whichthe reactants are delivered sequentially or simultaneously.

Embodiments of cyclical deposition have been described above as thedeposition of a binary compound of tantalum nitride utilizing pulses oftwo reactants. In the deposition of other elements or compounds, pulsesof two or more reactants may also be used.

While foregoing is directed to the preferred embodiment of the presentinvention, other and further embodiments of the invention may be devisedwithout departing from the basic scope thereof, and the scope thereof isdetermined by the claims that follow.

1. A chamber, comprising: a chamber body; a substrate support at leastpartially disposed within the chamber body and having a substratereceiving surface; a chamber lid comprising an expanding channelextending downwardly from a central portion of the chamber lid and atapered bottom surface extending radially from the expanding channel toa peripheral portion of the chamber lid, wherein the tapered bottomsurface and the expanding channel share a co-linear symmetry axis, andwherein the tapered bottom surface is shaped and sized to substantiallycover the substrate receiving surface; one or more valves in fluidcommunication with the expanding channel; and one or more gas sources influid communication with each valve.
 2. The chamber of claim 1, furthercomprising one or more gas conduits fluidly connecting the one or morevalves and the expanding channel and disposed normal to a longitudinalaxis of the expanding channel.
 3. The chamber of claim 2, wherein theone or more gas conduits are disposed at an angle to the longitudinalaxis of the expanding channel.
 4. The chamber of claim 1, wherein thetapered bottom surface comprises a surface selected from the groupconsisting of a straight surface, a concave surface, a convex surface,or combinations thereof.
 5. The chamber of claim 1, wherein theexpanding channel is shaped as a truncated cone.
 6. The chamber of claim1, wherein the expanding channel comprises an upper portion and a lowerportion, the upper portion having a smaller inner diameter than thelower portion.
 7. The chamber of claim 1, wherein a common gas source iscoupled to each valve and wherein separate gas sources are coupled toeach valve.
 8. The chamber of claim 1, further comprising a chokedisposed on the chamber lid adjacent a perimeter of the bottom surface.9. A chamber, comprising: a substrate support having a substratereceiving surface; a chamber lid comprising an expanding channelextending from a central longitudinal axis of the chamber lid andcomprising a tapered bottom surface extending radially from theexpanding channel to a peripheral portion of the chamber lid; one ormore gas conduits connected to an upper portion of the expandingchannel, wherein the one or more gas conduits are connected at an anglenormal to the expanding channel from a center of the expanding channel;one or more valves disposed below the expanding channel and coupled tothe expanding channel via the one or more gas conduits; and a chokedisposed on the chamber lid adjacent a perimeter of the tapered bottomsurface.
 10. The chamber of claim 9, wherein the one or more gasconduits are connected at an angle to the longitudinal axis of theexpanding channel.
 11. A gas delivery assembly, comprising: a chamberlid comprising an expanding channel extending downwardly from a centralportion of the chamber lid and a tapered bottom surface extending fromthe expanding channel to a peripheral portion of the chamber lid; one ormore gas conduits connected to an upper portion of the expandingchannel, wherein the one or more gas conduits are connected at an angleorthogonal from a longitudinal axis of the expanding channel; and one ormore valves disposed below the expanding channel and coupled to theexpanding channel via the one or more gas conduits.
 12. The gas deliveryassembly of claim 11, wherein the one or more gas conduits are angleddownwardly.
 13. The gas delivery assembly of claim 11, wherein the oneor more gas conduits are disposed normal to the longitudinal axis of theexpanding channel.
 14. The gas delivery assembly of claim 11, whereinthe tapered bottom surface comprises a surface selected from the groupconsisting of a straight surface, a concave surface, a convex surface,or combinations thereof.
 15. The gas delivery assembly of claim 11,wherein the expanding channel is shaped as a truncated cone.
 16. The gasdelivery assembly of claim 11, wherein the expanding channel comprisesan upper portion and a lower portion, the upper portion having a smallerinner diameter than the lower portion.
 17. The gas delivery assembly ofclaim 11, wherein a common gas source is coupled to each valve andwherein separate gas sources are coupled to each valve.
 18. The gasdelivery assembly of claim 11, further comprising a choke disposed onthe chamber lid adjacent a perimeter of the bottom surface.
 19. Achamber, comprising: a substrate support at least partially disposedwithin a chamber body and having a substrate receiving surface; achamber lid comprising an expanding channel extending downwardly from acentral axis of the chamber lid and a tapered bottom surface extendingradially from the central axis of the chamber lid from the expandingchannel to a peripheral portion of the chamber lid, the tapered bottomsurface shaped and sized to substantially cover the substrate receivingsurface, wherein the expanding channel and the tapered bottom surfaceare disposed symmetrically about the central axis; one or more valves influid communication with the expanding channel, each of the one or morevalves having a diaphragm; and one or more gas sources in fluidcommunication with each valve, wherein the diaphragm moves from an openposition to a closed position, or from a closed position to an openposition, in about 1.0 seconds or less.
 20. The chamber of claim 19,further comprising one or more gas conduits fluidly connecting the oneor more valves and the expanding channel and disposed normal to thecentral axis of the expanding channel.
 21. The chamber of claim 19,wherein the one or more gas conduits are disposed at an angle to thecentral axis of the expanding channel.
 22. The chamber of claim 19,wherein the tapered bottom surface comprises a surface selected from thegroup consisting of a straight surface, a concave surface, a convexsurface, or combinations thereof.
 23. The chamber of claim 19, whereinthe expanding channel is shaped as a truncated cone.
 24. The chamber ofclaim 19, wherein the diaphragm moves from the open position to theclosed position, or from the closed position to the open position, inabout 0.5 seconds or less.
 25. The chamber of claim 1, wherein each ofthe one or more valves have a diaphragm that moves from an open positionto a closed position, or from a closed position to an open position, inabout 1.0 seconds or less.
 26. The chamber of claim 9, wherein each ofthe one or more valves have a diaphragm that moves from an open positionto a closed position, or from a closed position to an open position, inabout 1.0 seconds or less.